I was working on a game script similar to this context. It involved characters resembling Cid, Cloud, Sephiroth, Aeris, Vincent, Yuffie, Tifa, Zell, Seifer, Squall, Riku, Sora, Ansem, Goofy, Donald, Mickey, and Sieg Wahrheit.

My story followed the events in Hollow Bastion just after Ansem discovered the Heartless. It had 13 different perspectives (like something out of SaGa Frontier) and you were able to see events in each scenario that other characters didn't see as there were always times when your party members would disappear and reappear. The main villain was a dark dude from some necrosphere thing, I forget exactly what it was. But it was cool. I don't know where the story is right now, but when I find it, I'll definitely finish it.

You're forced to play as one of three characters to begin with. Each time you beat the game, you unlock a character until the 13th becomes available. In this way, you're earning the right to re-play by beating the game to begin with.